arm64: move cpu_suspend_set_dbg_restorer() prototype to header

The cpu_suspend_set_dbg_restorer() function is called by the hw_breakpoint
code but defined in another file. Since the declaration is in the
same file as the caller, the compiler warns about the definition
without a prior prototype:

arch/arm64/kernel/suspend.c:35:13: error: no previous prototype for 'cpu_suspend_set_dbg_restorer' [-Werror=missing-prototypes]

Move it into the corresponding header instead to avoid the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20230516160642.523862-5-arnd@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: arndb

arch/arm64/include/asm/hw_breakpoint.h

@@ -154,4 +154,12 @@ static inline int get_num_wrps(void)
 						ID_AA64DFR0_EL1_WRPs_SHIFT);
 }
 
+#ifdef CONFIG_CPU_PM
+extern void cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int));
+#else
+static inline void cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int))
+{
+}
+#endif
+
 #endif	/* __ASM_BREAKPOINT_H */

arch/arm64/kernel/hw_breakpoint.c

@@ -973,14 +973,6 @@ static int hw_breakpoint_reset(unsigned int cpu)
 	return 0;
 }
 
-#ifdef CONFIG_CPU_PM
-extern void cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int));
-#else
-static inline void cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int))
-{
-}
-#endif
-
 /*
  * One-time initialisation.
  */